The first named storm of the 2018 hurricane season arrived prematurely Friday, energized by a roller coaster-like plunge in the upper atmosphere and promising heavy rain for South Florida.
Alberto, a subtropical storm that formed a week ahead of the official seasonal start date of June 1, was nearly stationary Friday night in the western Caribbean Sea, but is expected to begin a crawl north into the Gulf of Mexico on Saturday.
The National Hurricane Center has Alberto making landfall with estimated 65-mph winds late Monday between the western reach of Florida’s Panhandle and Lafayette, La. Storm-surge watches have been issued for areas near Horshoe Beach in Florida’s Big Bend to the mouth of the Mississippi River. A tropical storm watch also is in effect for Port St. Joe in Gulf County to Grand Isle, La.
Although Alberto is expected to stay west of the Peninsula, South Florida sits on its more robust eastern flank, meaning thunderstorms, drenching rains, gusting winds and isolated tornadoes are possible through at least Monday morning.
Palm Beach County’s highest risk for torrential rain and flooding is Saturday and Sunday, the National Weather Service said.
“Pretty much all of South Florida is in the bullseye for 5-plus inches of rain with some areas that could get 8 inches or more,” said Weather Underground co-founder Jeff Masters. “You will have this system in place for multiple days.”
A rainfall forecast from the South Florida Water Management District shows 6 to 8 inches of rain could pile up in Palm Beach, Broward and Miami-Dade counties, with up to 12 inches in Lee and Collier counties through Monday.
Only gradual strengthening is expected until Alberto moves farther into the Gulf of Mexico’s warm waters, where hurricane center forecasters predict its winds could intensify to 65 mph shortly before reaching the Gulf Coast.
Accuweather forecasters said there is a chance Alberto could become a weak hurricane if it slows down, enabling it to gather power from the Gulf’s warm loop current. Hurricane center forecasters noted in their 5 p.m. advisory that if the intensity forecast increases, hurricane watches could be issued for portions of the Gulf Coast.
Hurricane winds begin at 74 mph. Tropical storm force winds are between 39 and 73 mph.
“We’ve seen some weird things happen in this region of the Gulf,” said Ken Clark, a senior meteorologist with Accuweather. “It can bring some surprising intensification.”
While wind and waves will be a concern for areas in the Gulf Coast near landfall, rain will be South Florida’s biggest challenge, and communities are gearing up for days of showers.
With the ground already saturated from last week’s speedy ramp up of the rainy season, flooding and trees uprooted by winds gusting to 35 mph are a possibility, said Robert Molleda, National Weather Service warning coordination meteorologist in Miami.
A flood watch is in effect for all of South Florida through Sunday, and could be extended into Monday.
In Wellington, canals and swales were filled to the brim last week. On the south end of Wellington, an aging culvert collapsed, causing a dirt road to wash into a canal. In The Acreage, residents dealt with large amounts of standing water on properties. And in Loxahatchee Groves, already-troubled dirt roads became nearly impassable, with one road closed after part of it collapsed into a canal.
Wellington has had more than 14 inches of rain this month, with 12 of those inches falling last week.
After torrential downpours this past weekend, some localized flooding was reported around the village. Water did not breach any homes or businesses and all drainage systems are working as designed, officials said.
West Palm Beach is preparing for 3 to 5 inches of rainfall Saturday through Monday.
“We are not expecting any widespread flooding, but given the potential for flash floods, we want to make sure people follow guidelines with regards to standing or moving water,” said West Palm Beach Emergency Operations Director Brent Bloomfield.
Communities are asking residents to help reduce flooding by making sure nearby storm drains are free of leaves and yard waste is not in the street.
Whether Alberto remains a subtropical storm or becomes a tropical storm doesn’t make much of a difference in how it affects the forecast.
It was labeled a subtropical storm Friday because of its interaction with a sharp upper-level trough that is giving it power by causing air to rise, but is also limiting intensification with wind shear. Subtropical storms have characteristics of both mid-latitude cyclones – similar to the winter storms that travel west to east – and tropical cyclones that gain power through the convective energy of thunderstorms.
Subtropical storms were first given names from the six-year rotating list of tropical cyclone names in 2002.
Since 2007, six named storms have formed in the Atlantic in May, including Andrea in 2007, Arthur in 2008, Alberto and Beryl in 2012, Ana in 2015, and Bonnie in 2016, according to Colorado State University hurricane researcher Phil Klotzbach.
Molleda said even if Alberto reaches the Gulf Coast on Monday as forecast, a trailing band of moisture will continue to soak South Florida, meaning Memorial Day barbecuers should have a contingency plan.
“We won’t see much improvement,” Molleda said. “Monday doesn’t look too good.”
Palm Beach Post staff reporters Kristina Webb, Tony Doris, Kevin Thompson and Sarah Peters contributed to this story.